1. Field of the Invention
The present invention relates to printing devices such as laser printers, ink jet printers or copying machines which print or copy characters or figures. More specifically, the present invention relates to a printer device which allows recorded items printed or copied on a medium such as paper to disappear or de-color on a timely basis depending on the urgency or priority of the items or how long the tasks need to be resolved or processed.
2. Description of Related Art
In modern office environments, people work with documents with different priorities or deadlines. For example, a manager may have to read dozens of documents every day and process them before the end of the day. Programmers have to read thousands of lines of code; lawyers have to read through the details of cases. All of these tasks require printing the whole of, or a part of, the documents in a format that people can read and process easily.
Before the popularity of computers, people had to print everything on paper to read and process. Now, with the development of personal computers and network technology, more and more people use computers and office automation software to work and process directly within the computer—so called paperless systems. With the help of email, the Internet and instant messengers, this can greatly improve working efficiencies.
However, the computer is not a panacea. Not everyone likes using computers and not all works are suitable for processing by computers. One reason is that the computer monitor screen may contain harmful radiation and may be bad for people's health. Some computer software is still not easy to use. Also, some people just prefer to print long documents on paper and then read the document from the paper without using computers.
Furthermore, reading from the computer screen for too long may harm one's eyes. Paper materials are still useful in many cases, just like even now with emails and many online tools, there are still many meetings held face-to-face due to their ease of use. Printed paper or documents still play an important role in modern society. However, out of the many printed documents, there is only a small percentage that require permanent storage or persistence. The majority of printed materials are for temporary use and can be discarded after being read, reviewed, and processed after a certain time.
On the other hand, many tasks or printed documents have deadlines associated with them. For example, a case needs to be reviewed by the lawyer before the court hearing; a programmer must finish reviewing the source code before release; a scientist must finish reading a paper before continuing his work. However, time management has always been a difficult task for ordinary people. It is always hard for a person to start processing the documents assigned to him if he is not consistently reminded. In this case, if there is a way to push or force the person to finish the work before certain deadlines, the efficiency of the person can be greatly improved.
U.S. Pat. No. 6,905,538 to Auslande entitled “Invisible ink jet inks” discloses a water-based invisible red fluorescent inks providing machine-readable, inverse contrast invisible images that can be printed using conventional ink jet printers. The inks employ rare earth complexed ligand fluorophores having narrow excitation and emission spectra. In one embodiment the images are printed with an ink comprising water and a water-soluble organic fluorescent fluorophore, which when printed and dried on paper is invisible to the eye and fluoresces in the green to infrared range, e.g., from about 550 to 1200 nm, when irradiated with short wave length UV radiation, e.g., from 230 nm to 280 nm. The highly specific excitation and emission rates, coupled with a high inverse contrast on papers of all colors, makes them particularly useful as ink jet inks for postal and other purposes. That patent relates to the steps of making an invisible ink.
U.S. Pat. No. 6,915,103 to Blume entitled “System for enhancing books with special paper” discloses a system for enhancement of books or other reading material including an item of reading material, printed on a substrate having a substantially invisible, machine-readable coordinate grid. A pointing device is configured to detect the coordinate grid on the substrate when placed in proximity thereto. An output device receives input from the pointing device to determine the location of the pointing device relative to the substrate, and provides output corresponding to contents of the reading material at the location. The output may be in the form of audio and/or video. The disclosure relates to the application of invisible inks and invisible, machine-readable coordinate grids in books.
U.S. Pat. No. 4,404,922 to Morane et al. entitled “Ageing indicator” discloses an ageing indicator that compares a closed sachet of one or more closed tubes of a material which is slightly permeable to a fluid contained in the sachet or tube. The rate of permeation of the fluid through the sachet-like assembly tube wall depends upon temperature and time of exposure to that temperature so the quantity of fluid loss is indicative of temperature and time; the ageing capable of then being detected either by measuring a column of the liquid in a tube or by observing the appearance or disappearance of printed indicia in the sachet. The disclosure relates to the use of invisible inks to indicate aging.
U.S. Pat. No. 4,162,164 to Lin entitled “Cyanine dye based high saturation sympathetic ink having time delayed disappearance” discloses an ink that is intensely colored in solution with the vehicle of the ink. The ink “disappears” or becomes invisible to the naked eye after a period of time has elapsed from the application of the ink to a record document. The ink being utilized to identify an unsatisfactory character on a document such as a MICR check which has had an erroneous character printed which must be corrected before being correctly machine read. The patent discloses formulas for making invisible or disappearing ink.
U.S. Pat. No. 5,290,346 to Fujioka discloses an ink for an ink jet printer capable of decoloring a recorded image or changing a color of the recorded image to thereby save resources, improve economy, and improve functionality. As a coloring composition of the ink, an organoboron salt of cyanine dye and an ammonium salt of organoboron are employed in combination. After printing, the recorded image is decolored by irradiating near infrared light emissions onto a recording surface of a recording paper. As a result, the recording paper can be reused. This patent relates to decoloring inks that can be used for printers.
U.S. Pat. No. 5,215,956 to Kawashima entitled “Color changing print” discloses plural areas printed by using plural types of color changing inks which develop into different colors from the substantially invisible colorless state by reaction with a color changing agent. By the emergence of print from colorlessness and by giving changes in the appearing colors, unexpectedness and entertainingness are provided so that an attractive education may be realized. This patent discloses inks that can change colors instead of disappearing.
U.S. Pat. No. 5,104,448 to Kruse entitled “Jet printing ink compositions and methods” discloses jet printing ink compositions characterized as having low volatility, low viscosity and low variation of viscosity with respect to temperature. The compositions comprise a coloring agent dissolved or dispersed in a liquid vehicle which is preferably substantially free of added water and is a propylene glycol ether or an ethylene glycol butyl ether in which the coloring agent is soluble or dispersible. This patent discloses a special kind of disappearing ink.
U.S. Pat. No. 5,568,986 to Sugai entitled “Printer device” discloses a printer device with an erasing portion for erasing recorded items of a medium on which characters or figures have been recorded, and a recording portion for printing or copying the surface of the medium having passed through the erasing portion by color fading ink or toner. This patent relates to printers that use decoloring inks.
U.S. Pat. No. 5,362,592 to Murofushi et al. relates to a decolorizable toner including a resin binder, a near infrared ray-absorbing dye, a decolorizing agent and a light fastness stabilizer, and a process for preparing the decolorizable toner, which includes the steps of mixing the near infrared ray-absorbing dye and the light fastness stabilizer with the resin binder, and then mixing the decolorizing agent therewith. The decolorizable toner has excellent light stability during its production or storage and excellent decolorizing property. This patent relates to decoloring toners for printers.
U.S. Pat. No. 5,922,115 to Sano et al. discloses a decolorizable ink and printer. Decolorizable ink consists of an ink composition dispersed in a solvent, the ink composition comprising a color former, a developer and a decolorizer, wherein the color former and developer are in a colored state by interaction between them and the decolorizer has a property to dissolve preferentially the developer when the ink composition is melted. This patent relates to decoloring ink and printers.
What is needed then is a time limited printing method that can print documents that automatically fade after a certain time to achieve a variety of purposes including improving work efficiency by associating the time with deadlines and paper recycling.